This paper presents the results of a series of self-healing experiments conducted on reinforced mortar beams containing adhesive-filled glass reservoirs. An overview of the findings of the preliminary investigation stage of experiments is given in addition to the results of a parametric study which investigates the effect of the level of reinforcement and loading rate on the amount of self-healing. Results show that both primary and secondary healing occurs during the first and second loading cycles respectively. Qualitative results also show clear evidence of the occurrence of crack-healing following the first loading cycle and new crack formation during the second loading cycle. The long-term motivation for this work is to provide data suitable for the development of a numerical material model for the autonomic healing process in cementitious materials.

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Materials for Life (M4L) was a 3 year, EPSRC funded, research project carried out by the Universities of Cardiff, Bath and Cambridge to investigate the development of self-healing cementitious construction materials. This paper describes the UK's first site trial of self-healing concrete, which was the culmination of that project. The trial comprised the in-situ construction of five concrete panels using a range of self-healing technologies within the site compound of the A465 Heads of the Valleys Highway upgrading project. Four self-healing techniques were used both individually and in combination with one another. They were: (i) the use of microcapsules developed by the University of Cambridge, in collaboration with industry, containing mineral healing agents, (ii) bacterial healing using the expertise developed at Bath University, (iii) the use of a shape memory polymer (SMP) based system for crack closure and (iv) the delivery of a mineral healing agent through a vascular flow network. Both of the latter, (iii) and (iv), were the product of research undertaken at Cardiff University. This paper describes the design, construction, testing, and monitoring of these trial panels and presents the primary findings of the exercise. The challenges that had to be overcome to incorporate these self-healing techniques into full-scale structures on a live construction site are highlighted, the impact of the different techniques on the behavior of the panels when subject to loading is presented and the ability of the techniques used to heal the cracks that were generated is discussed.

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The presence of cracks has a negative impact on the durability of concrete by providing paths for corrosive materials to the embedded steel reinforcement. Cracks in concrete can be closed using shape memory polymers (SMP) which produce a compressive stress across the crack faces. This stress has been previously found to enhance the load recovery associated with autogenous self-healing. This paper details the experiments undertaken to incorporate SMP tendons containing polyethylene terephthalate (PET) filaments into reinforced and unreinforced 500 × 100 × 100 mm structural concrete beam samples. These tendons are activated via an electrical supply using a nickel-chrome resistance wire heating system. The set-up, methodology and results of restrained shrinkage stress and crack closure experiments are explained. Crack closure of up to 85% in unreinforced beams and 26%–39% in reinforced beams is measured using crack-mouth opening displacement, microscope and digital image correlation equipment. Conclusions are made as to the effectiveness of the system and its potential for application within industry.

Historically construction materials have been designed to meet a fixed specification and material degradation has been viewed as inevitable and mitigated for through expensive maintenance regimes. Material scientists have recently begun developing materials which have the ability to adapt and respond to their environment, drawing on their knowledge and familiarity of biological systems. This fundamental change in material design philosophy has resulted in the creation of a whole host of ‘smart’ materials, including self-healing materials. The development of self-healing materials is reviewed in this paper, together with definitions of common terminology. A brief summary of the construction industry is given, together with a synopsis of the main issues of durability relating specifically to cementitious materials. Specific focus is then given to both autogenic (natural) and autonomic (manufactured) healing processes within cementitious materials. The paper concludes with a summary of self-healing materials, an overview of their potential use within the construction sector, and recommendations to this sector for future uptake of these new and innovative materials.